cherry-pick 332bab18d

compiler/Java_CodeGen.jrag

@@ -337,6 +337,9 @@ aspect User_Types {
   when parentDecl() != null && getType().isUserType()
   to Decl.references() 
   for parentDecl();
+
+  syn boolean Decl.hasReferences();
+  eq Decl.hasReferences() = !references().isEmpty();
 }
 
 aspect Java_Class {
@@ -358,7 +361,7 @@ aspect Java_Class {
   }
  
   public void Decl.Java_emitUserTypeDeps(Java_env env, String via, boolean outputCode) {
-    if( !references().isEmpty() ) {
+    if( hasReferences() ) {
         Iterator<Decl> it = references().iterator();
         while(it.hasNext()) {
             Decl t = it.next();
@@ -398,17 +401,26 @@ aspect Java_Class {
       env.println("import se.lth.control.labcomm"+env.verStr+".SampleType;");
       if (getType().Java_needInstance()) {
           env.println("import java.io.IOException;");
-      env.println("import se.lth.control.labcomm"+env.verStr+".Encoder;");
           env.println("import se.lth.control.labcomm"+env.verStr+".Decoder;");
+      }
+      if (getType().Java_needInstance() || hasReferences()) {
+          env.println("import se.lth.control.labcomm"+env.verStr+".Encoder;");
           env.println();
       }
-      //For types not needing an instance, currently just an empty class is generated
+
+      // For types without references and not needing an instance, 
+      // currently just an empty class is generated
 
       env.println("public class " + getName() + " implements SampleType {");
       env.println();
 
-    if (getType().Java_needInstance()) {
       env.indent();
+      if(hasReferences()) {
+        // XXX Java_emitRegisterEncoder(env);
+        // XXX Java_emitDispatcher(env, false);
+      }
+  
+      if (getType().Java_needInstance()) {
         getType().Java_emitInstance(env);
         Java_emitEncoder(env);
         Java_emitDecoder(env);
@@ -461,7 +473,36 @@ aspect Java_Class {
     env.println();
 
     Java_emitRegisterEncoder(env);
+    Java_emitDispatcher(env, true);
+    Java_emitEncoder(env);
+    Java_emitDecoder(env);
+
+    env.println("private static byte[] signature = new byte[] {");
+    env.indent();
+    SignatureList signature = signature(env.version);
+    for (int i = 0 ; i < signature.size() ; i++) {
+      String comment = signature.getComment(i);
+      if (comment != null) {
+        env.println(signature.getIndent(i) + "// " + comment);
+      }
+      byte[] data = signature.getData(i);
+      if (data != null) {
+        env.print(signature.getIndent(i));
+        for (int j = 0 ; j < data.length ; j++) {
+	  env.print(data[j] + ", ");
+        }
+        env.println();
+      }
+    }
+    env.unindent();
+    env.println("};");
+    env.unindent();
+    env.println();
+    env.println("}");
+ 
+  }
 
+  public void Decl.Java_emitDispatcher(Java_env env, boolean canDecodeAndHandle) {
     env.println("private static class Dispatcher implements SampleDispatcher {");
     env.indent();
     env.println(); 
@@ -483,15 +524,25 @@ aspect Java_Class {
     env.unindent();
     env.println("}");
     env.println(); 
+    env.println("public boolean isSample() {");
+    env.indent();
+    env.println("return "+canDecodeAndHandle+";");
+    env.unindent();
+    env.println("}");
+    env.println(); 
     env.println("public void decodeAndHandle(Decoder d,");
     env.println("                            SampleHandler h) throws Exception {");
     env.indent();
+    if( canDecodeAndHandle) {
         if (isVoid()) {
           env.println(getName() + ".decode(d);");
           env.println("((Handler)h).handle_" + getName() + "();"); 
         } else {
           env.println("((Handler)h).handle_" + getName() + "(" + getName() + ".decode(d));"); 
         }
+    } else {
+        env.println("throw new Exception(\"A typedef has no handler, the corresponding method on the sample class should be called.\");");
+    }
     env.unindent();
     env.println("}");
     env.println("");
@@ -499,30 +550,6 @@ aspect Java_Class {
     env.println("}");
     env.println("");
 
-    Java_emitEncoder(env);
-    Java_emitDecoder(env);
-    env.println("private static byte[] signature = new byte[] {");
-    env.indent();
-    SignatureList signature = signature(env.version);
-    for (int i = 0 ; i < signature.size() ; i++) {
-      String comment = signature.getComment(i);
-      if (comment != null) {
-        env.println(signature.getIndent(i) + "// " + comment);
-      }
-      byte[] data = signature.getData(i);
-      if (data != null) {
-        env.print(signature.getIndent(i));
-        for (int j = 0 ; j < data.length ; j++) {
-	  env.print(data[j] + ", ");
-        }
-        env.println();
-      }
-    }
-    env.unindent();
-    env.println("};");
-    env.unindent();
-    env.println();
-    env.println("}");
  }
 
   public void TypeDecl.Java_emitEncoder(Java_env env) {